The RAM Quick-Grip™ with Yoke Clamp Mount Twist-Lock™ Suction Cup consists of a yoke clamp base, double socket arm and spring loaded cradle for supporting most phones. The clamp base will accommodate rails in diameter from 0.625" to 1.25". The double ball and socket design provides adjustment points at both ends of the socket arm with the turn of a single knob, allowing you to set your phone to the optimal viewing position.